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Light-based treatment is clearly enjoying a surge in popularity. There are now available illuminated devices for everything from dermatological concerns and fine lines as well as aching tissues and periodontal issues, recently introduced is a dental hygiene device outfitted with small red light diodes, marketed by the company as “a major advance for domestic dental hygiene.” Globally, the market was worth $1bn in 2024 and is projected to grow to $1.8bn by 2035. There are even infrared saunas available, where instead of hot coals (real or electric) heating the air, the infrared radiation heats your body itself. According to its devotees, it feels similar to a full-body light therapy session, stimulating skin elasticity, relaxing muscles, relieving inflammation and long-term ailments while protecting against dementia.

The Science and Skepticism

“It sounds a bit like witchcraft,” observes a neuroscience expert, a scientist who has studied phototherapy extensively. Of course, some of light’s effects on our bodies are well established. Sunlight enables vitamin D production, essential for skeletal strength, immune function, and muscular health. Light exposure controls our sleep-wake cycles, additionally, stimulating neurotransmitter and hormone production during daytime, and winding down bodily functions for sleep as it fades into night. Daylight-simulating devices are a common remedy for people with seasonal affective disorder (Sad) to elevate spirits during colder months. Clearly, light energy is essential for optimal functioning.

Types of Light Therapy

Whereas seasonal affective disorder devices typically employ blue-range light, consumer light therapy products mostly feature red and infrared emissions. During advanced medical investigations, such as Chazot’s investigations into the effects of infrared on brain cells, finding the right frequency is key. Light is a form of electromagnetic radiation, spanning from low-energy radio waves to high-energy gamma radiation. Light-based treatment uses wavelengths around the middle of this spectrum, the highest energy of those being invisible ultraviolet, followed by visible light encompassing rainbow colors and infrared light visible through night vision technology.

Ultraviolet treatment has been employed by skin specialists for decades for addressing long-term dermatological issues like vitiligo. It modulates intracellular immune mechanisms, “and reduces inflammatory processes,” says Dr Bernard Ho. “Considerable data validates phototherapy.” UVA penetrates skin more deeply than UVB, whereas the LEDs we see on consumer light-therapy devices (typically emitting red, infrared or blue wavelengths) “tend to be a bit more superficial.”

Safety Considerations and Medical Oversight

Potential UVB consequences, like erythema or pigmentation, are understood but clinical devices employ restricted wavelength ranges – meaning smaller wavelengths – which decreases danger. “Therapy is overseen by qualified practitioners, thus exposure is controlled,” notes the specialist. Most importantly, the devices are tuned by qualified personnel, “to confirm suitable light frequency output – unlike in tanning salons, where oversight might be limited, and emission spectra aren’t confirmed.”

Consumer Devices and Evidence Gaps

Red and blue LEDs, he notes, “don’t have strong medical applications, but could assist with specific concerns.” Red wavelength therapy, proponents claim, improve circulatory function, oxygen uptake and cell renewal in the skin, and promote collagen synthesis – a key aspiration in anti-ageing effects. “Studies are available,” states the dermatologist. “Although it’s not strong.” In any case, amid the sea of devices now available, “we’re uncertain whether commercial devices replicate research conditions. Optimal treatment times are unknown, ideal distance from skin surface, if benefits outweigh potential risks. Numerous concerns persist.”

Targeted Uses and Expert Opinions

One of the earliest blue-light products targeted Cutibacterium acnes, bacteria linked to pimples. Research support isn’t sufficient for standard medical recommendation – even though, notes the dermatologist, “it’s commonly used in cosmetic clinics.” Some of his patients use it as part of their routine, he observes, though when purchasing home devices, “we just tell them to try it carefully and to make sure it has been assessed for safety. Unless it’s a medical device, standards are somewhat unclear.”

Advanced Research and Cellular Mechanisms

At the same time, in innovative scientific domains, researchers have been testing neural cells, discovering multiple mechanisms for infrared’s cellular benefits. “Pretty much everything I did with the light at that particular wavelength was positive and protective,” he says. The numerous reported benefits have generated doubt regarding phototherapy – that it’s too good to be true. But his research has thoroughly changed his mind in that respect.

Chazot mostly works on developing drug treatments for neurodegenerative diseases, however two decades past, a physician creating light-based cold sore therapy requested his biological knowledge. “He created some devices so that we could work with them with cells and with fruit flies,” he says. “I was pretty sceptical. This particular frequency was around 1070 nanometers, that nobody believed did anything biological.”

What it did have going for it, however, was its ability to transmit through aqueous environments, allowing substantial bodily penetration.

Mitochondrial Effects and Brain Health

Growing data suggested infrared influenced energy-producing organelles. Mitochondria produce ATP for cell function, producing fuel for biological processes. “Mitochondria exist throughout the body, including the brain,” notes the researcher, who concentrated on cerebral applications. “Studies demonstrate enhanced cerebral circulation with light treatment, which is consistently beneficial.”

With 1070 treatment, cellular power plants create limited oxidative molecules. In limited quantities these molecules, notes the scientist, “triggers guardian proteins that maintain organelle health, protect cellular integrity and manage defective proteins.”

All of these mechanisms appear promising for treating a brain disease: free radical neutralization, anti-inflammatory, and waste removal – autophagy representing cellular waste disposal.

Present Investigation Status and Expert Assessments

Upon examining current studies on light therapy for dementia, he states, several hundred individuals participated in various investigations, including his own initial clinical trials in the US